Photographic plate.



A. HERZKA. PHOTOGRAPHIO PLATE. APPLICATION FILED Nov. 1, 1909.

Patented N0v.28,1911.

UNITED sTATEs PATENT oEEioE.'

A DOL HERZKA, 0F DRESDEN', GERMANY.

PHOTOGRAPHE PLATE'.

Specification oLetters Patent, Application led November 1, 1909. Serial No. 525,740

Patented Nov. 28, 1911.'

To all @cham it may concern:

Be it known that I, ADOLF HERZKA, a.l

.subject of the German Emperor, and residing at Dresden, German Empire, have invented certain new and useful Improvements in PhotographicPlates, of which the following is a specification.

For the purpose of preventing halation various methods have been tried, including.

lhasnot, however, proved satisfactory, for

the gelatin layer, owing to its relatively considerable thickness, when hard is liable to bind the color in such manner that the latter is not properly dissolved out again on developing. The reduction of the sensitive- -ness to light caused by the'color penetrating the emulsion layer renders exposure of the plate for a considerabletime necessary, and the colored layer cannot sufficiently stop the light during so long an interval. Thus rays pass through and halation to a greater or less extent is the result.

According to my invention I overcome the drawbacks 1n question by distributing the colored gelatin over both sides of the emulsion support, instead of applying it only to the one side thereof, as has hitherto been the practice.

In order to make my invention more readily understood, I have illustrated it on the accompanying drawing, which shows a cross-section through my new 4antihalation plate, and in which ,the referencecharacter denotes the transparent sup ort, of glass, celluloid, or the like, b the lght-absorbing material, and c the sensitized emulsion.

'I-he advanta e of my new method is that 50 the layer can e hardened by any suitable gelatin hardening agent without ensuing inconvenience. For by distributing the gela- .tin over both sides of the support the thickness ofthelayer has been reduced by -one 55.` half; and after the hardening, which im:

parts compactness to the material, the thickness is reduced, it may be, even below one half. -Tlie layer is` now sufliciently thin to admit of the color being properly dissolvedI out in spite vof the hardened condition. De-

spite the thinness of the layer the hardness bestows such strength that the layer remains quite neutral with respect to the emulsion,

so that none-of the color entersthe latter.

In this manner the full sensibility to lightof the emulsion is maintained and an eX-l tremelyk short exposure will be found adequate. y

In carrying out theinew method in'prac-l 70 tice, the emulsion support (glass plate or hn) may be immersed in a vessel containing the previously colored gelatin in liquid state. The support is then withdrawn and the gelatin, which will now be distributed 755 over both sides, is hardened by any approved means; The support so prepared 1s nowallowed to dry thoroughly, Whereu on the emulsion is applied 1n any wel -known mamer. 1 1 f d em o in e atin o corres on ing consistendy si, cogatigng of any desired thickness can be attained.

-Having thus described my invention, I declare that what `I claim as new and desire to secure by Letters Patent is v A photographic plate, comprising a transparent support, a relatively thin light-abv sorbing la er on each face thereof, and a coating o said light-absorbing layers, substantially as set forth. r A

In testimon whereof Ialix my signature in presence o two witnesses.

' ADOLF HERZKA, Witnesses:

PAUL Anus, CLRE SIMON.

sensitized emulsion on one of 

